OverCharging help
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OverCharging help
Hi I have a 1973 F250, I put a multimeter to the battery and its charging 17 volts, I have changed the positive cable, starter to starter switch cable, cleaned engine ground to cab, also put in a standard motor products voltage regulator. one thing I think is odd as soon as I turn the key to the on position before even starting the truck is that the charge gauge goes all the way to the right to C.
After starting the truck it stays toward the C, when driving down the road it bounces all over the place and never stays in one spot.
I got the alternator tested at oreilly they said its good but it had a high charge of 15.7 volts on their machine with a average of 14.6 which seems a bit high to me. its a 60 amp alt but I was thinking maybe my truck needs a 40 amp.
After starting the truck it stays toward the C, when driving down the road it bounces all over the place and never stays in one spot.
I got the alternator tested at oreilly they said its good but it had a high charge of 15.7 volts on their machine with a average of 14.6 which seems a bit high to me. its a 60 amp alt but I was thinking maybe my truck needs a 40 amp.
Postmaster
Joined: Nov 2011
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It sounds like a wiring, ground or short in the alternator... and needs fixed before you run it as 17 volts will cook the battery and other stuff. Alternator rated amps does not matter for this... properly controlled, even a 140 or 200 amp alternator should work fine.
A few suggestions on step by step.
First easy thing to do is make sure the VR is well grounded. Clean off the metal behind the mounting screws or run a dedicated ground wire to a mounting screw. Next is trace and visually inspect the two light wires attached to the back of the alternator. Look for chafing, shorts or breaks. Next is remove the two small terminals from the back of the alternator and tape them up. Give it a try. Voltage should be low - in the 12 volt range. If it is still high you likely have a shorted/bad alternator.
A few suggestions on step by step.
First easy thing to do is make sure the VR is well grounded. Clean off the metal behind the mounting screws or run a dedicated ground wire to a mounting screw. Next is trace and visually inspect the two light wires attached to the back of the alternator. Look for chafing, shorts or breaks. Next is remove the two small terminals from the back of the alternator and tape them up. Give it a try. Voltage should be low - in the 12 volt range. If it is still high you likely have a shorted/bad alternator.
FTE Chapter Leader
Joined: May 2001
Posts: 3,322
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From: Rhode Island
Where did you get the voltage regulator from?
I had a charging issue that I chased for years in my mustang. It turned out the voltage regulator I installed wasn't correct for the year 302 even though It looked exactly like the one it replaced.
I had a charging issue that I chased for years in my mustang. It turned out the voltage regulator I installed wasn't correct for the year 302 even though It looked exactly like the one it replaced.
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